AI was fine, what i meant by combat mechanics was guns, grenades and such. i felt like i had little control over my guns. everything burst fired, recoil was horrendous. it felt like i was just spraying bullets willy-nilly when slomo wasn't on. only FPS game i've ever played where i was completely unable to mitigate recoil with my mouse. the grenades might be what irritated me the most though. i died SO many times from my own grenade when either i'd pop out, throw it, and pop back, only to have it bounce off the wall back at me because of the retardedly long delay, or hit a door frame for the same effect because the point man threw like a girl playing slow pitch softball. i DID really like the mele though, they kindof screwed those up a bit in 2.
acutally, i take that back. i remember now what annoyed me the most, the way the replicas seemed to become invulnerable when they did their "getting shot" staggering animations.